ADP1873ARMZ-0.3-R7 Analog Devices Inc, ADP1873ARMZ-0.3-R7 Datasheet - Page 29

• Manufacturer Part Number: ADP1873ARMZ-0.3-R7
• Description: 300kHz, Light Load Eff Enabled
• Manufacturer: Analog Devices Inc

Specifications of ADP1873ARMZ-0.3-R7

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 300kHz
• Duty Cycle: 84%
• Voltage - Supply: 2.75 V ~ 20 V
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Frequency-max: 300kHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ADP1873ARMZ-0.3-R7TR

Loss Calculations
Duty cycle = 1.8/12 V = 0.15
R
t
V
C
Q
R
BODY(LOSS)
ON (N2)
IN
GATE
F
N1, N2
= 0.84 V (MOSFET forward voltage)
= 3.3 nF (MOSFET gate input capacitance)
= (0.15 × 0.0054 + 0.85 × 0.0054) × (15 A)
= 1.215 W
= 20 ns × 300 × 10
= 151.2 mW
P
P
= 1.5 Ω (MOSFET gate input resistance)
N1,
BODY
= 17 nC (total MOSFET gate charge)
= 5.4 mΩ
N2(CL)
= 20 ns (body conduction time)
(
LOSS
=
)
=
[
D
t
×
BODY
R
t
N1(ON)
SW
3
(
LOSS
× 15 A × 0.84 × 2
)
+
×
(
1
I
LOAD
−
D
)
×
×
V
R
F
N2(ON)
×
2
]
×
2
I
2
LOAD
Rev. A | Page 29 of 40
P
= 300 × 10
= 534.6 mW
= (5.12 × (300 × 10
(5.5 × (300 × 10
= 77.13 mW
P
P
P
= 1.215 W + 151.2 mW + 534.6 mW + 77.13 mW +
3.15 mW + 675 mW + 56.25 mW
= 2.62 W
[
P
P
V
SW (LOSS)
COUT
CIN
LOSS
DR
DCR
DD
(
= ( I
LOSS
(
= P
×
LOSS
= ( I
(
)
f
RMS
= f
)
N1, N2
SW
=
RMS
=
3
)
SW
[
C
DCR
V
2
× 1.5 Ω × 3.3 × 10
)
lowerFET
× ESR = (7.5 A)
2
+ P
DR
× R
× ESR = (1.5 A)
3
×
×
BODY (LOSS)
×3.3 ×10
GATE
(
I
f
V
2
LOAD
3
SW
× 3.3 × 10
DD
× C
C
= 0.003 × (15 A)
upperFET
+
TOTAL
+ P
I
−9
BIAS
×5.5 + 0.002))
2
SW
ADP1872/ADP1873
V
−9
)
× 1 mΩ = 56.25 mW
× I
2
−9
]
DR
× 1.4 mΩ = 3.15 mW
+ P
× 15 A × 12 × 2
× 5.12 + 0.002)) +
LOAD
+
DCR
I
BIAS
× VIN × 2
+ P
2
)
= 675 mW
]
DR
+
+ P
COUT
+ P
CIN